Replace public operators operator==() and operator!=() of QCborValue
to friend method comparesEqual().
Replace public operator<() of QCborValue to friend method
compareThreeWay().
Use QT_CORE_REMOVED_SINCE to get rid of current comparison methods
and replace them with a friend.
Delete #if 0 && __has_include(<compare>) blocks,
since they are not required anymore.
Task-number: QTBUG-120300
Change-Id: I884ff6ce2a71618b0e3eaa907f0852f93c2a073c
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>